ISSN:0002-9505    

DOI:10.1119/1.16512

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.16513

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

A formula, apparently new, is derived for the spatial rotation of a free rigid body during one periodTof its body angular momentum vector. This formula has the structure of recent phase formulas of Berry [Proc. R. Soc. London Ser. A392, 45–57 (1984); Sci. Am.259(6), 46–55 (1988)] and Hannay [J. Phys. A18, 221–230 (1985)]; namely, it consists of a geometric and a dynamic part. It is derived by applying Stokes’ theorem to a certain closed curve in phase space.

ISSN:0002-9505    

DOI:10.1119/1.16514

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

The study of driven mechanical harmonic oscillations in the undergraduate student laboratory is greatly enhanced by the new high standard of precision achieved by computerized data acquisition and analysis. In this paper, two experiments are described that investigate transient behavior. In one experiment, beats are observed when the driving frequency is not equal to the resonant frequency; and in the other experiment, oscillations are observed to grow linearly with time at the resonant frequency. Steady‐state behavior is also investigated. Both amplitude and phase are measured as functions of frequency.

ISSN:0002-9505    

DOI:10.1119/1.16515

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

A study is described to evaluate the Graduate Record Examination (GRE) as an indicator of learning by undergraduate physics majors. Measures were obtained of the overlap of the Graduate Record Examination in physics with the curriculum as it is taught to physics majors in US colleges and universities. The output of the project, for a given subfieldfand setjof institutions, was two numbersRj, f1andRj, f2. These two numbers estimated the extent to which (1) forRj, f1, the curriculum prepares students at institutionsjto take that part of the GRE which covers subfieldfand (2) forRj, f2, the GRE covers the materials in subfieldftaught in the curriculum of institutionsj. The subfieldsf were mechanics, electricity and magnetism, statistical mechanics and thermodynamics, modern physics, and ‘‘other’’ (including experimental, mathematical, and solid‐state physics). The institutionsjwere grouped into four categories: ‘‘top graduate’’ (those with the 20 best‐ranked graduate programs); ‘‘top undergraduate’’ (those participating in the Oberlin Conference on College Science); ‘‘random graduate’’ (other institutions with graduate programs); and ‘‘random undergraduate’’ (other institutions without graduate programs). Generally the results show that the GRE does not cover the entire curriculum (low values ofR2) for any institutional type. With regard to the coverage of the GRE by the curriculum (R1values), there are significant differences between institutions of different types. Institutions with graduate programs have curricula that cover the modern physics and statistical mechanics aspects of the GRE significantly better than institutions without graduate programs.

ISSN:0002-9505    

DOI:10.1119/1.16517

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Magnetic charges are used to discuss electromagnetic phenomena in which the symmetry between the electric and magnetic fields is fully displayed. A simple derivation of the transformation equations of the fields (E,B) is given. It is shown that the Lorentz force as an axiom can be replaced by the simpler definition that the force on a particle of electric chargeqand magnetic chargegin its rest frame isqE+gB(whereEandBare the rest frame fields).

ISSN:0002-9505    

DOI:10.1119/1.16518

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

A simple means of deriving Maxwell’s equations and the Lorentz force law from their symmetries is presented. The same approach is then used to derive the classical theory of magnetic monopoles and dual‐charged particles.

ISSN:0002-9505    

DOI:10.1119/1.16519

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

First‐order and second‐order phase transitions are demonstrated using soap‐film models. The models consist of two‐dimensional parallel plates or three‐dimensional frameworks in which film patterns are maintained. By making the sizes of the frameworks variable, it is possible to induce switching between film patterns analogous to transitions between phases. These phase changes are discussed thermodynamically and using a catastrophe theory model.

ISSN:0002-9505    

DOI:10.1119/1.16520

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

Starting from the equations of general relativity, equations similar to those of electromagnetic theory are derived. It is assumed that the particles are slowly moving (v≪c), and the gravitational field is sufficiently weak that nonlinear terms in Einstein’s field equations can be neglected. For static fields, the analogy to electrostatics and magnetostatics is very close. Results are compared with those of a previous derivation by Braginsky, Caves, and Thorne [Phys. Rev. D15, 2047–2068 (1977)]. These results lead to very simple derivations of the Lense–Thirring precession [Phys. Z.19, 156–163 (1918)] and the spin‐curvature force of Papepetrou [Proc. R. Soc. London Ser. A209, 248–258 (1951)] and Pirani [Acta Phys. Pol.15, 389–405 (1956)].

ISSN:0002-9505    

DOI:10.1119/1.16521

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP

摘要:

A variational approach to the calculation of the two lowest eigenvalues of Schrödinger’s equation for the double‐oscillator potential is presented. A family of two‐parameter double‐Gaussian trial functions provides an alternative to the exact series expansions for the energy eigenfunctions and yields energy estimates of high accuracy.

ISSN:0002-9505    

DOI:10.1119/1.16522

出版商:American Association of Physics Teachers    

年代:1991

数据来源: AIP